1. Field of the Invention
The present invention relates to a mobile communication system using a mobile terminal device which is capable of accessing both a mobile communication network and a local network simultaneously and a gateway device for relaying between a fixed communication network and a local network.
2. Description of the Related Art
In conjunction with the rapid spread of cellular phones and the Internet, the Internet service using a cellular phone as a terminal has been developed by the mobile carriers. This is a service in which a module for processing a communication protocol called TCP/IP used in the Internet is provided in the cellular phone so as to enable WWW service, e-mail delivery, static image and video image data transfer, etc. This service has an advantage in that it becomes possible to freely access not just information closed within the communication service provider but also various information available on the Internet that is spreading worldwide, and for this reason the number of users of this service is increasing rapidly.
Now, the cellular phone Internet service that has an enormous number of users encounters a serious problem regarding how to assign addresses to terminals. Currently, the Internet faces with the problem of IP address shortage in view of the ever increasing number of nodes (routers and terminals), and in the current IPv4, it has been customary to use an address system called private address that is closed within an organization for accesses in an enterprise network and to use global addresses only for accesses to the external of the organization by utilizing the address conversion. Similarly, in the case of the cellular phone Internet service, it is currently customary to use the private address within the cellular phone network by providing an address conversion device (NAT: Network Address Translator) at a border between the IP packet network of the cellular phone company and the global Internet.
On the other hand, the next generation IP specification called IPv6 is currently under the development. The IPv6 can accommodate far more nodes compared with the IPv4 by expanding the IP address from a 32 bits width as used in the IPv4 to a 128 bits width. Similarly, in the case of the cellular phone Internet service, it is possible to assign unique global addresses to all terminals by adopting the IPv6. In this way, communications using a seamless end-to-end connection that does not require a relay device such as NAT on the communication path can be realized by using a wide address space, and it is expected to be advantageous in many aspects including the security and the quality of service (QoS). Also, the IPv6 has a function called address autoconfiguration for automatically generating an address from a network ID managed by each router and a unique ID of the device, and this is expected to make the management of hosts easier.
Also, recently, in conjunction with the advance of the wireless technology, the techniques for locally connecting various types of devices by a wireless network have been developed. One such technique is the wireless standard called Bluetooth which connects devices in short distances by using 2.4 GHz unlicensed radio band. In the Bluetooth, devices can carry out mutual data communications by forming an ad-hoc network called pico-net. The similar network specification also includes the HomeRF which is intended for use in the home network.
Now, consider a situation in which the packet service based on the IPv6 scheme is introduced into the cellular phone network, for example, such that the Internet access via the cellular phone network and the ISP (Internet Service Provider) network is possible according to the IPv6. Here, it is assumed that, in the home network, the Internet access is made via a gateway device and this gateway device is connected with various devices through a local (wireless) network such as Bluetooth or the like. On the other hand, it is also assumed that the portable terminal is capable of accessing the Internet via the cellular phone network and the portable terminal is also capable of accessing the Bluetooth network by using another communication interface. Namely, consider a situation where the user of the cellular phone receives services by accessing the IP network of the cellular phone network while the user is located outside the home, and receives services by accessing the gateway connected to the fixed ISP network, via the Bluetooth network, while the user is located inside the home.
Here, when an attempt to access the Bluetooth network inside the home is made by using a portable terminal, the access is not necessarily possible for every portable terminal. Considering that it is inside the home, it is possible to consider a control such that the access is possible for those portable terminals that have an access right or an access qualification such as portable terminals owned by the family members, but the access to the Bluetooth network is not permitted for any other portable terminals. However, this is a rather inflexible policy because the Internet access using the home network is not permitted at all for visitors other than the family members.
In particular, in the case of the fixed access network that is not necessarily limited to the home network, it is preferable to use a control such that those terminals that have the membership qualification can access for free, and even non-member terminals can access upon payment of appropriate fee. Else, at least when the terminal with no permission given in advance is accessing the access network, there is a need to acquire the log information of that access so as to realize the monitoring for preventing the illegal act by the malicious user, even if no fee is to be charged.
In other words, it is preferable to permit access even for the terminal with no permission given in advance after carrying out the prescribed charging or log acquisition processing, rather than simply permitting access only for those portable terminals that have carried out the user registration.
There is also a problem regarding how an access made from a device in the fixed network or from the Internet via the gateway in the opposite direction should be connected to a resource in the cellular phone network. Namely, the cellular phone user is responsible for all the accesses in general, so that there is a need for the cellular phone to function as proxy after carrying out the appropriate authentication sequence.
For example, there is a need to prevent an attack to or an illegal use of the resource on the cellular phone network side by verifying the authenticity of the access by communicating a prescribed message or authentication code with the cellular phone or by making an entry into a cellular phone network access list provided in the gateway, such that the portable terminal permits the access to the resource in the cellular phone network only when the authenticity is verified and filters out any other messages.